This introductory chapter discusses the specificities of crisis-management during the COVID-19 pandemic in Europe and presents the main purpose of this book. It highlights the importance of collecting comparative and legislative data on pandemic containment to be able to evaluate emergency public policies. It then presents the EXCEPTIUS dataset, its methods and the indicators it uses to capture the stringency of COVID-19 exceptional policies. Based on legal data from 32 European countries, this dataset documents a high degree of variability between these countries, particularly regarding the concentration of power and the reduction of individual liberties.